Abstract
Hydrogels are suitable for osteochondral defect regeneration as they mimic the viscoelastic environment of cartilage. However, their biomechanical properties are not sufficient to withstand high mechanical forces. Therefore, we have prepared electrospun poly-ε-caprolactone-chitosan (PCL-chit) and poly(ethylene oxide)-chitosan (PEO-chit) nanofibers, and FTIR analysis confirmed successful blending of chitosan with other polymers. The biocompatibility of PCL-chit and PEO-chit scaffolds was tested; fibrochondrocytes and chondrocytes seeded on PCL-chit showed superior metabolic activity. The PCL-chit nanofibers were cryogenically grinded into microparticles (mean size of about 500 µm) and further modified by polyethylene glycol–biotin in order to bind the anti-CD44 antibody, a glycoprotein interacting with hyaluronic acid (PCL-chit-PEGb-antiCD44). The PCL-chit or PCL-chit-PEGb-antiCD44 microparticles were mixed with a composite gel (collagen/fibrin/platelet rich plasma) to improve its biomechanical properties. The storage modulus was higher in the composite gel with microparticles compared to fibrin. The Eloss of the composite gel and fibrin was higher than that of the composite gel with microparticles. The composite gel either with or without microparticles was further tested in vivo in a model of osteochondral defects in rabbits. PCL-chit-PEGb-antiCD44 significantly enhanced osteogenic regeneration, mainly by desmogenous ossification, but decreased chondrogenic differentiation in the defects. PCL-chit-PEGb showed a more homogeneous distribution of hyaline cartilage and enhanced hyaline cartilage differentiation.
Highlights
The healing of osteochondral defects is limited and is accompanied by the ingrowth of fibrous tissue into the defect
In our previous study we showed that polyvinyl alcohol (PVA) nanofibers embedded either in a composite collagen/hyaluronate/fibrin gel or fibrin alone showed increased Young’s modulus compared to composite gel or fibrin without nanofibers. (In the present study we concentrated on composite scaffolds with natural sources of growth factors from the present platelets.) poly-ε-caprolactone (PCL) nanofibers embedded in a collagen/hydroxyapatite foam significantly improved the elastic modulus of the scaffolds [15]
We found that platelet rich plasma (PRP) improved mesenchymal stem cells (MSC) proliferation, and PCL MPs slowed down gel degradation compared to gel without MPs [47]
Summary
The healing of osteochondral defects is limited and is accompanied by the ingrowth of fibrous tissue into the defect. The formed fibrocartilage cannot withstand the mechanical loading applied on the joint for an extended period; in non-treated defects, the degeneration symptoms progress. Standard surgical techniques, such as subchondral drilling or microfractures, are based on perforating the bone plate, which leads to bleeding and the migration of stem cells from the bone marrow into the defect. These techniques may decrease symptoms, but are not able to restore physiological hyaline cartilage [1,2]. The limitations of chondrocytes implantation include invasive surgery for cartilage harvesting, the risk of dedifferentiation during in vitro cultivation, decreased quality of chondrocytes during ageing and the quality of chondrocytes which depend on the health of the donor
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
